Where can I find a 3-axis gimbal?

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azraphale
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Where can I find a 3-axis gimbal?

Post by azraphale »

I'm building a logic-controlled set of lights (actually for use on motorcycles), and it requires that the lights be pivot-able in all 3 axes over about 90 degrees of travel in each axis. I'd like something very compact, so a concentric 3-axis gimbal system is what I've been searching for, to no avail (think of the radar mounts in fighter's noses, or the FLIR or camera pods on helicopters and UAVs).

Here's a simple 3-axis gimbal to give you an idea.

Image

However, I am having the damndest time finding a source for a gimbal. The lights are about the size of a webcam each, and one will be mounted on each fork leg. So a 3-axis gimbal for a webcam-sized camera should work fine. I will be supplying my own logic and stepper motors, and if need be I guess I'll design and manufacture my own gimbals, but it seems like there should be an off-the-shelf unit that would work well at a reasonable price. I just can't seem to find it!

Any assistance would be welcome; if you are a machinist (or know one) who can develop and produce in small quantities (20-40 units per order, perhaps?) for a reasonable price, I'm game. :D Aluminum or carbon fiber (likely pre-fab panels cut and joined) would be my first choices, and I might be willing to offer titanium if the market showed demand for the extra cost of the "bling".
Engineer1138
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Post by Engineer1138 »

Do you have a drawing? There are two places I can think of that may be helpful:
the Home Shop Machinist BBS: http://bbs.homeshopmachinist.net/forumdisplay.php?f=3
or the CNCZone RFQ forum:
http://www.cnczone.com/forums/forumdisplay.php?f=74

I'd consider doing a few for you, but I don't know if I have the machining skill just yet to do complex work for other people :-)

Titanium is going to cost an arm and a leg, though. Not just the material: it takes more time & care to work with and you'll be paying for that. Carbon fiber you can probably DIY yourself. Have you considered fiberglass? I've been thinking of using it for projects ever since I noticed it was available at Home Depot of all places

I don't read this BBS as often as I used to so if you have a question about possible other sources just go to www.cedarlakeinstruments.com and send me an email from the "Contact" link (I hate putting my email address in forums due to the amount of spam that results).
Engineer1138
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Post by Engineer1138 »

p.s.,
ignore the site in my .sig: it's obsolete and I can't get into my profile to change it.
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azraphale
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Post by azraphale »

Thanks for the reply. :)

I've come up with a preliminary drawing, but details remain to be worked out. I think I am going to go with a stainless steel pivot shaft and a PTFE bushing on the two outer gimbal axes, so I need to work out the thickness of each of those two components; I also think I may embed the stepper motors for the two outer gimbals in the gimbals themselves, which would look a lot cleaner and make it easier for me to weather-seal the steppers. So as a preliminary step, assuming I will be making my own gimbal setup, I need to have those three things spec'd out and in hand to get accurate dimensions to work from. But I have a clear idea of what I want design-wise now, assuming everything on the prototypes works the way I want it to, and doesn't flex too much from vibration.

I had a problem with Solidworks and had to completely uninstall it on my machine, but I intent to get everything back on track this weekend and I can have some preliminary drawings to give an idea of what I'll be trying for if I end up doing it all myself. I will likely stick to aluminum, although I may do something with carbon fiber combined with some aluminum parts down the road. The carbon is more of a "bling" thing, since this setup won't really be supporting very much weight to speak of. I suppose if I can produce CAD files for a part in aluminum, I could produce CAD files to make a mold with the part's shape as negative space, and make carbon replacements, but if I can do regular straight tube sections in carbon with the joints and motor housings in CNC aluminum, that will be plenty of bling without a lot of added design and manufacturing costs. Fiberglass doesn't seem like a good cost/benefit ratio, given that it won't have the visual appeal of either billet or CF, and will take more effort to lay up by hand than simply having a CNC shop crank out billet pieces that are stiffer and don't weigh much more. I do have a number of machine shops I can work through, both owned and run by friends and very locally to myself. I'd just figured that someone would have made some sort of generic 3-axis gimbal system in various sizes that I could adapt. :D Ah, well! If anyone needs a 3-axis gimbal system that's lightweight and can handle a quarter pound of payload, I might be able to set you up if I end up pushing this all the way through to production. :D

The steppers I've found are damned expensive, though... That's probably the biggest sticking point to something like this. The ones I have picked out thus far for my BoM are from Danaher Motion. Their part no. is 42M048C2U, and Digi-Key has them for $18.70 each. They are 12v unipolar, 42x49.5mm case size, 7.5 degrees/step and have a 10.4 oz-in holding tq. I think they will get the job done for me, but with six of them per installation on a motorcycle, the BoM costs are eye-opening! I'll happily take advice on where to get the best prices on quality stepper motors! Because of the cost and complexity of the extra drive circuitry, I think sticking with unipolar is a good idea, and since I'll be installing these on motorcycles, 12v is best. The smaller the cases, the better, and I don't think I'll need much more angular precision than 7.5 deg/step (although if I can get it at a price point, I'll take it). I thought about servos, but getting strong ones with metal gears seems to end up costing a good bit more than stepper motors.
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Clyde Crashkop
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Post by Clyde Crashkop »

I have been wanting to and should build something like that as an application for my own product but I only need 2 axis. Maybe this would motivate me and we can work something out. If you PM me, I will look into it.
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